/*
 * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
 *
 * This software is open source.
 * See the bottom of this file for the licence.
 */

package org.dom4j;

import org.dom4j.tree.AbstractNode;
import org.dom4j.tree.DefaultNamespace;
import org.dom4j.tree.NamespaceCache;

/**
 * <p> <code>Namespace</code> is a Flyweight Namespace that can be shared
 * amongst nodes. </p>
 * 
 * @author <a href="mailto:jstrachan@apache.org">James Strachan </a>
 * @version $Revision: 1.2 $
 */
public class Namespace extends AbstractNode
{
   /** Cache of Namespace instances */
   protected static final NamespaceCache CACHE = new NamespaceCache();

   /** XML Namespace */
   public static final Namespace XML_NAMESPACE =
      CACHE.get("xml", "http://www.w3.org/XML/1998/namespace");

   /** No Namespace present */
   public static final Namespace NO_NAMESPACE = CACHE.get("", "");

   /** The prefix mapped to this namespace */
   private String prefix;

   /** The URI for this namespace */
   private String uri;

   /** A cached version of the hashcode for efficiency */
   private int hashCode;

   /**
    * DOCUMENT ME!
    * 
    * @param prefix is the prefix for this namespace
    * @param uri is the URI for this namespace
    */
   public Namespace(String prefix, String uri)
   {
      this.prefix = (prefix != null) ? prefix : "";
      this.uri = (uri != null) ? uri : "";
   }

   /**
    * A helper method to return the Namespace instance for the given prefix and
    * URI
    * 
    * @param prefix DOCUMENT ME!
    * @param uri DOCUMENT ME!
    * 
    * @return an interned Namespace object
    */
   public static Namespace get(String prefix, String uri)
   {
      return CACHE.get(prefix, uri);
   }

   /**
    * A helper method to return the Namespace instance for no prefix and the URI
    * 
    * @param uri DOCUMENT ME!
    * 
    * @return an interned Namespace object
    */
   public static Namespace get(String uri)
   {
      return CACHE.get(uri);
   }

   public short getNodeType()
   {
      return NAMESPACE_NODE;
   }

   /**
    * DOCUMENT ME!
    * 
    * @return the hash code based on the qualified name and the URI of the
    *         namespace.
    */
   public int hashCode()
   {
      if(hashCode == 0)
      {
         hashCode = createHashCode();
      }

      return hashCode;
   }

   /**
    * Factory method to create the hashcode allowing derived classes to change
    * the behaviour
    * 
    * @return DOCUMENT ME!
    */
   protected int createHashCode()
   {
      int result = uri.hashCode() ^ prefix.hashCode();

      if(result == 0)
      {
         result = 0xbabe;
      }

      return result;
   }

   /**
    * Checks whether this Namespace equals the given Namespace. Two Namespaces
    * are equals if their URI and prefix are equal.
    * 
    * @param object DOCUMENT ME!
    * 
    * @return DOCUMENT ME!
    */
   public boolean equals(Object object)
   {
      if(this == object)
      {
         return true;
      }
      else if(object instanceof Namespace)
      {
         Namespace that = (Namespace) object;

         // we cache hash codes so this should be quick
         if(hashCode() == that.hashCode())
         {
            return uri.equals(that.getURI()) && prefix.equals(that.getPrefix());
         }
      }

      return false;
   }

   public String getText()
   {
      return uri;
   }

   public String getStringValue()
   {
      return uri;
   }

   /**
    * DOCUMENT ME!
    * 
    * @return the prefix for this <code>Namespace</code>.
    */
   public String getPrefix()
   {
      return prefix;
   }

   /**
    * DOCUMENT ME!
    * 
    * @return the URI for this <code>Namespace</code>.
    */
   public String getURI()
   {
      return uri;
   }

   public String getXPathNameStep()
   {
      if((prefix != null) && !"".equals(prefix))
      {
         return "namespace::" + prefix;
      }

      return "namespace::*[name()='']";
   }

   public String getPath(Element context)
   {
      StringBuffer path = new StringBuffer(10);
      Element parent = getParent();

      if((parent != null) && (parent != context))
      {
         path.append(parent.getPath(context));
         path.append('/');
      }

      path.append(getXPathNameStep());

      return path.toString();
   }

   public String getUniquePath(Element context)
   {
      StringBuffer path = new StringBuffer(10);
      Element parent = getParent();

      if((parent != null) && (parent != context))
      {
         path.append(parent.getUniquePath(context));
         path.append('/');
      }

      path.append(getXPathNameStep());

      return path.toString();
   }

   public String toString()
   {
      return super.toString() + " [Namespace: prefix " + getPrefix()
         + " mapped to URI \"" + getURI() + "\"]";
   }

   public String asXML()
   {
      StringBuffer asxml = new StringBuffer(10);
      String pref = getPrefix();

      if((pref != null) && (pref.length() > 0))
      {
         asxml.append("xmlns:");
         asxml.append(pref);
         asxml.append("=\"");
      }
      else
      {
         asxml.append("xmlns=\"");
      }

      asxml.append(getURI());
      asxml.append("\"");

      return asxml.toString();
   }

   public void accept(Visitor visitor)
   {
      visitor.visit(this);
   }

   protected Node createXPathResult(Element parent)
   {
      return new DefaultNamespace(parent, getPrefix(), getURI());
   }
}

/*
 * Redistribution and use of this software and associated documentation
 * ("Software"), with or without modification, are permitted provided that the
 * following conditions are met:
 * 
 * 1. Redistributions of source code must retain copyright statements and
 * notices. Redistributions must also contain a copy of this document.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * 
 * 3. The name "DOM4J" must not be used to endorse or promote products derived
 * from this Software without prior written permission of MetaStuff, Ltd. For
 * written permission, please contact dom4j-info@metastuff.com.
 * 
 * 4. Products derived from this Software may not be called "DOM4J" nor may
 * "DOM4J" appear in their names without prior written permission of MetaStuff,
 * Ltd. DOM4J is a registered trademark of MetaStuff, Ltd.
 * 
 * 5. Due credit should be given to the DOM4J Project - http://www.dom4j.org
 * 
 * THIS SOFTWARE IS PROVIDED BY METASTUFF, LTD. AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL METASTUFF, LTD. OR ITS CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * 
 * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
 */
